Airhead Timing Chain...

I tried to get on snowbum's site to answer this question, but all I got was an "Earthlink-This page is not found" page. AH!

Anyway...I'm starting in on some maintenance prior to riding season and one of the things on the list is the front main seal (weepy, weepy). I'm planning to do the Enduralast kit anyway, so I figured while I was in there...replace the seal, etc.

When does the timing chain usually need replacing on these bikes? Mine is a 76 r90/6 with ~35-45000 miles on it (bum odometer). I had some troubling vibration at the end of the season last year and I had a hell of a time setting the timing at the beginning of the season. I don't know if those are symptoms of the bike or my glaring stupidity regarding such matters.

And, a bonus question: Does one need to remove the engine to do the timing chain as Clymer's instructs?

Trouble setting the timing?.....was this with a brand new set of points? I couldn't get my timing retarded far enough the last time I replaced my points. I thought that it might be related to my timing chain....then somebody mentioned on a thread that there were Chinese made points on the market that had a rubbing block that was taller than normal----which would give you too much advance. I ran out of riding season before I could get it all straightened out. I'm planning to start out next season with another set of new NON-CHINESE points......

When does the timing chain usually need replacing on these bikes? Mine is a 76 r90/6 with ~35-45000 miles on it (bum odometer). Snip....

And, a bonus question: Does one need to remove the engine to do the timing chain as Clymer's instructs?

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Theres your key right there. Unknown mileage.

If you timing chain is stretched, you could have any of the symptoms that you're reporting. Plus, if you don't know how many miles are on the bike, you might want to swap that old chain out anyway. I would.

I was taught that 35K to 40K miles was about the service life for a double row chain,so I would certainly think about changing it at this point.

It ain't that big a job. Just make sure you have all the new parts before you take things apart and whatever you do, don't drop the Master Link.

And, a bonus question: Does one need to remove the engine to do the timing chain as Clymer's instructs?

Click to expand...

Hmmm, no need to remove the engine to change the timing change...on an '88. But those have master links. I believe the sprockets need to be pulled on older bikes. Is that right? Still doesn't seem like the engine would need to be removed. Removing the fork legs may make things a bit easier.

Sorry, I realize that's not too helpful.

Okay, how's this. I believe you have an old link to Snowbum's site. Try this:

No need to remove the engine for timing chain replacement. I replaced the timing chain in my r75 at 35k and my r90 at 50k. In both instances I heard the chain slack hitting the case and noticed the timing marks on the fly wheel jump.

Hmmm, no need to remove the engine to change the timing change...on an '88. But those have master links. I believe the sprockets need to be pulled on older bikes. Is that right? Still doesn't seem like the engine would need to be removed. Removing the fork legs may make things a bit easier.

Sorry, I realize that's not too helpful.

Okay, how's this. I believe you have an old link to Snowbum's site. Try this:

No need to pull the engine whatsoever. Get a new chain with a masterlink. WAY easier job. Buy a BMW chain. Some of them out there are junk IMO. If you need a new chain, you almost certainly need a new crank sprocket. The dual row cam sprockets wear too so look carefully at it as well. The chains last about 2/3rds as long as they should installed on worn sprockets.

I find the duplex chains to be a real pain in the arse to change and have never managed to fit a split link in one successfully with the sprockets in place. The only way I've been able to do them is to pull the cam and engine sprocket, fit the link's in the chain and refit the lot, with the chain in place, at the same time, obviously that needs the oil pump and it's woodruff key to come out which in turn needs the gearbox and clutch removing. The later single row chain was a quantum leap forward in terms of simplicity.

Getting the link in there with the sprockets in place is tricky but it is a LOT easier than pulling the sprockets just to get the link in. Your the first person I have ever heard go about it your way. Whatever gets 'er done!

I haven't got the patience for fiddling about like that. Out of frustration I nearly stoved the tank in with a hammer the first time I tried it. Much better to plan ahead and do the camchain at some convenient time when something else is being done.

I do the single row chains in place. Nice and easy with them but sod the duplex chains...

The first one I did got me really frustrated to say the least. The most important thing I found, was the place you choose to couple the ends up. Looking from the front, I think around 10 oclock. Since then I have done about 5 of them and they usually go right together. A screwdriver with a curve bent on the end makes the clips easier to snap off and on. I think I slip a thin piece of aluminum between the chain and block to steady things.

Last time I changed the chain on my 81 R100RS I stumbled over a new trick that makes it easier.

I put the timing chain in place, with join over one of the holes in the casing to make room to get the joining link in from the rear.

But before putting the new joining link in from the rear, I put the old joining link in partway from the front. It is real easy to push the link in from the front.

The old link is then holding the new chain ends exactly the right distance apart, making it much easier to slide the new link in from the rear, displacing the old link as the pins come through. (Be sure and catch the old link before it disappears into the sump someplace.)

This trick makes it soooo much easier than wrestling with the two ends of the chain and a pair of longnose pliers and the new link all at the same time.

That is a very good photo of a very worn sprocket. To a somewhat lesser extent usually, I see worn crank sprockets like that almost every time I replace a chain. I have never seen a worn simplex cam sprocket myself although I did see a picture of one on the net. I see them on duplex setups about half the time. The duplex setups just don't wear as well for some reason.